Maximilian Hasler: "I wonder whether it makes sense to create the "new
S" for any subset of {0...18} which yields a nontrivial result.... But
why not, after all this will yield a finite and relatively small
number of additional sequences..."
me: "Aren't there a total of 524287 subsets? Do we know that most of
these are trivial?"
Maximilian Hasler: "Not quite - e.g., any set without terms in
[10,...,18] leads to a
finite sequence..."
That's 1023 down, 523264 to go.